Concrete bridge deckings are commonly coated with a protective layer of asphalt (up to 15 cm thick), uniformly spread under heavy rolling equipment, which may weigh 10 metric tons or more. This asphalt layer is exposed to extremes of weather throughout the year, and will eventually develop cracks, some so small as to be practically invisible, others much larger. All are harmful, in that they permit liquid water to penetrate down to the concrete surface, where it freezes in winter and causes sizable portions of the asphalt layer to spall away. These adverse factors (freeze-shattering, traffic impact, chloride disintegration from de-icing salt, etc.) result in serious damage to the concrete traffic surface and eventually require major repairs.
Aside from asphalt-coated concrete surfaces, bridge concrete in the form of superstructure, parapets, crash barriers, etc., is also subject to attack, viz., from air- or moisture-borne industrial chemicals; spattered de-icing salt; and carbonation, i.e., gradual penetration of atmospheric carbon dioxide which then reacts with the alkaline materials in the concrete and attacks reinforcement in the concrete.
To inhibit the aforesaid destruction, it is conventional in concrete bridge construction and maintenance to apply a bridge deck membrane (BDM) to the concrete surface before laying down asphalt. Several BDM's are available. Polyurethane has been tried.
A BDM should meet a number of technical and economic criteria. It should:
(1) be impermeable to liquid water from above, yet be sufficiently permeable to permit small amounts of water vapor to escape from the concrete substrate; PA1 (2) be solventless; PA1 (3) be easily applied, preferably sprayable; PA1 (4) have good adhesion to concrete; PA1 (5) have low chloride penetration; PA1 (6) be stable to concrete alkali; PA1 (7) be stable under conditions of asphalt application - hard, but not brittle, yet be sufficiently flexible to cope with dimensional changes generated by temperature differentials and bridge movements; be able to tolerate application of asphalt at 170.degree. C under a 10-ton roll; PA1 (8) provide superior adhesion of asphalt as applied to the BDM; PA1 (9) be resistant to asphalt migration (i.e., tendency of low molecular weight hydrocarbons in asphalt to migrate into the BDM, weakening and/or destroying it). PA1 (10) have competitive raw material costs; PA1 (11) not discolor concrete; PA1 (12) have prolonged life on exposed surfaces (e.g., vertical surfaces and other surfaces not asphalt-coated); PA1 (13) be tough enough within a reasonable time for construction crews to walk on it. PA1 Triethylene diamine PA1 N-methyl morpholine PA1 N-ethyl morpholine PA1 Diethyl ethanolamine PA1 1-methyl-4-dimethylamino ethyl piperazine PA1 3-methoxy-N-dimethyl propyl amine PA1 N-dimethyl-N'-methyl isopropyl propylene diamine PA1 N,N-diethyl-3-diethyl amino propylamine PA1 N,N-dimethyl benzyl amine PA1 Dicyclohexylmethylamine PA1 2,4,6-tris dimethylaminomethylphenol PA1 N,N-dimethyl cyclohexylamine PA1 Triethylamine PA1 Tri-n-butylamine PA1 1,8-diaza-bichloro[5,4,0]-undecene-7 PA1 N-methyl diethanolamine PA1 N,N-dimethyl ethanolamine PA1 N,N-dimethyl cyclohexylamine PA1 N,N,N'N'-tetramethyl-ethylene diamine PA1 1,4-diaza-bicyclo-[2,2,2]-octane PA1 N-methyl-N'-dimethylaminoethyl-piperazine PA1 Bis-(N,N-diethylaminoethyl)-adipate PA1 N,N-diethylbenzylamine PA1 Pentamethyldiethylene triamine PA1 N,N,N'-tetramethyl-1,3-butanediamine PA1 1,2-dimethylimidazole PA1 2-methylimidazole PA1 Stannous chloride PA1 Dibutyl tin di-2-ethyl hexoate PA1 Stannous octoate PA1 Dibutyl tin dilaurate PA1 Trimethyl tin hydroxide PA1 Dimethyl tin dichloride PA1 Dibutyl tin diacetate PA1 Dibutyl tin oxide PA1 Tributyl tin acetate PA1 Tetramethyl tin PA1 Dimethyl dioctyl tin PA1 Tin ethyl hexoate PA1 Tin laurate PA1 Dibutyl tin maleate PA1 Dioctyl tin diacetate PA1 Zinc octoate PA1 Phenyl mercuric propionate PA1 Lead octoate PA1 Lead naphthenate PA1 Copper naphthenate PA1 (1) the novel combination of Components A and B as set forth in generic and specific formulations herein; PA1 (2) the processes (generic and specific) of mixing together Components A and B aforesaid; PA1 (3) the resins (generic and specific) resulting from PA1 (2) above; PA1 (4) process of coating a substrate with the resins of (3) above. Substrates of particular interest are metals and concrete, e.g., bridge decking. PA1 (5) coated metal or concrete articles resulting from (4) above; PA1 (6) overall process of protecting metals or concrete bridge decking by applying the resins of (3) above to metals or concrete, as the case may be; PA1 (7) as an article, bridge decking comprising concrete-polyurethane-asphalt laminate, the polyurethane being the resin of (3) above.